When New England took the field Friday night in Philadelphia in its first preseason game, it was Aaron Dobson, Josh Boyce and Kenbrell Thompkins lining up with Danny Amendola, Tom Brady and the first-team offense, not veteran Julian Edelman. Either Edelman has been passed by the rookies, or Bill Belichick determined Edelman wasn’t ready to take snaps with the first team after missing so much time in the spring and summer with a foot injury.